<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script src="https://unpkg.com/vue@next"></script>
<div id="app">
    <span>{{lastName}}</span>
    <div>{{fullName}}</div>
</div>
<script>
    const vueOpt = {
        data(){
            return {
                lastName:'default'
            }
        },
        computed:{
            fullName:{
                get(){
                    return this.lastName;
                },

                set(newValue){
                    this.lastName = newValue;
                }
            }
        }
    }

    const vm = Vue.createApp(vueOpt).mount('#app');

    setTimeout(()=>{
        vm.fullName = 'Kobe'
    }, 1000)
</script>
</body>
</html>
